1. Field of the Invention
The present invention relates to an image forming apparatus and an image forming method using a liquid developer and a photo-conductive substance.
2. Description of the Related Art
A conventional image forming apparatus using a liquid developer electrostatically or magnetically forms a latent image on a surface of an imiage forming body using a photoreceptor or a dielectric substance which are photosensitive substances, or an image forming body such as a magnetic recording body, and then selectively adheres the liquid developer onto the latent image to develop the image. The image forming apparatus then transfers an image of the liquid developer (developed image) which has been developed on the surface of the image forming boy onto a recording sheet, and thereafter fixes the developed image as transferred on the recording sheet by heat. With this process, image formation is completed.
In the image forming apparatus of this type, there is used a developing unit for supplying the liquid developer to the image forming body on which the latent image has been formed to form the developed image. An example of the conventional developing mant of this type will be described. A developing unit which is disclosed in Japanese Patent Unexamined Publication No. Hei 2-306275 published in Dec. 19, 1990 supplies the liquid developer to a developing roller through a supply roller prom a vessel in which the liquid developer is accommodated to remove a surplus developer by a squeeze roller. A developing unit which is disclosed in Japanese Patent Urexamined Publication No. Hei 6-214466 published in Aug. 5, 1994 makes a photo-conductive substance mosve while a liquid toner vessel, a developing roller and a squeege roller ate brought close to a surface of the photo-conductive substance on which an electrostatic latent image has been formed in the stated order, to thereby form the electrostatic image into a visual image through a liquid toner.
Also, a developing unit which is disclosed in Japanese Patent Unexamined Publication No. Hei 2-277086 published in Nov. 13, 1990 includes a supply slit that is disposed opposite to an image forming body on which an electrostatic latent image has been formed and erects a liquid toner toward the image forming body, and a recovery slit that recovers a supply toner. Further, a developing unit which is disclosed in Japanese Patent Unexamined Publication No. Hei 4-233566 published in Aug. 21, 1992 includes a vacuum device for recovering an air and a liquid carrier which is disposed tightly close to a surface of a photo-conductive member with a gap therebetween before a developed image is transferred onto a sheet after an electrostatic latent image formed on the photo-conductive member has been developed by a liquid developer.
In the developing units of the conventional image forming apparatuses as described above, the liquid developer is selectively supplied toward the latent image in accordance with the electrostatic latent image which is formed prior to development, to thereby permit an image section to which the liquid developer is adhered and a non-image section to which no liquid developer is adhered to be formed. The conventional developing units of this type must be designed in such a imanner that a liquid toner (liquid developer) of the quantity with which a sufficient image density is obtained is supplied to the image section, but the liquid toner is not supplied to the non-image section for preventing an image noise from occurring. Thus, because the liquid developer must be selectively supplied, the conventional developing units get complicated in construction. Also, as disclosed in Japanese Patent Unexamined Publication No. Hei 4-233566, there is required an image noose evading unit such as She vacuum unit for recovering the surplus liquid toner after development with the result that a complication is more increased.
The use of the image noise evading unit makes not only the construction of the un.it complicated but also the size of the unit increase, which causes to the costs to be increased and the reliability to be lowered. On the other hand, in the case of using a dielectric substance for the image forming body, a latent image can be formed through one process by a linear electrostatic head, whereas in the case of using a photo-conductive substance such a photoreceptor, there is required a process for uniformly charging the photo-conductive substance before light exposure.
Further, the image -Lorming apparatus normally requires a cleaning section that cleans the surface of the image forming body in order to recycle an image carrier, and also as occasions demand, requires a removal section. Therefore, such an image forming apparatus is not economical in practical use.